This document introduces Open Refine, an open source tool for cleaning and profiling messy data. It discusses how data from various sources can be inconsistent and inaccurate, and how Open Refine allows users to visualize their data, manipulate it to correct errors, and learn about the nature of the data. The basics of Open Refine involve using its interface and built-in transformations as well as custom functions like GREL and regular expressions to clean and restructure data.

1. OPEN REFINE TO PROFILE
AND CLEAN UP YOUR
MESSY DATA

2. THE WOES OF DATA
NOTE ALL DATA ARE MADE EQUAL!
DATA ARE CREATED FROM A VARIETY OF SOURCES:
• AUTOMATICALLY GENERATED
• MANUALLY CREATED AND MANAGED
• SCRAPPED FROM THE WEB
• TAKEN FROM ANOTHER SOURCE
• ETC.
EACH SOURCE TYPICALLY HAS ITS OWN METHOD OF HANDLING DATA.
THEREFORE DATA SOURCES ARE OFTEN HETEROGENEOUS, WHICH CREATES
INCONSISTENT AND INACCURATE DATA. FURTHER, THERE IS NO INFORMATION
PROVIDED ABOUT THE DATA TO HELP BETTER UNDERSTAND WHAT THE DATA ARE
ABOUT.

3. WHAT TO DO?
ESSENTIALLY, YOU ARE LOOKING FOR CONSISTENT AND ACCURATE
DATA. TO DO THIS, THERE ARE OPTIONS:
• CREATE A SCRIPT TO CLEAN DATA
• HAVE SOMEONE CLEAN YOUR DATA
• USE AN APPLICATION TO HELP YOU CLEAN YOUR DATA
TODAY, WE’RE GOING TO LOOK AT OPEN REFINE, AN APPLICATION
THAT CAN HELP YOU CLEAN YOUR DATA.

4. WHAT IS OPEN REFINE?
OPEN REFINE ORIGINATED WITH METAWEB TECHNOLOGIES AND THEN
GOOGLE. FORMERLY KNOWN AS FREEBASE GRIDWORKS, IT BECAME
KNOWN AS GOOGLE REFINE AND THEN OPEN REFINE.
IT IS A FULLY OPEN SOURCE APPLICATION.
YOU CAN DOWNLOAD IT AT: HTTP://OPEN
REFINE.ORG/DOWNLOAD.HTML

5. OPEN REFINE AND THE WOES OF DATA
WHETHER YOU HAVE HETEROGENEOUS DATA OR DATA YOU’RE
UNFAMILIAR WITH, OPEN REFINE CAN HELP WITH:
• DATA CLEANUP
• CORRECT INCONSISTENCIES AND INACCURACIES
• DATA PROFILING
• CREATE AN ANALYSIS OF UNFAMILIAR DATA BY LEARNING WHAT THE
DATA ARE

6. 2 BASIC OPERATIONS OF OPEN REFINE
BOTH DATA CLEANUP AND DATA PROFILING RELY ON A DATABASE,
CALLED FREEBASE, TO VISUALIZE AND MANIPULATE YOUR DATA.
VISUALIZING YOUR DATA INCLUDES BEING ABLE TO SEE THE “TYPE”
OF DATA. IS IT A DATE, NUMBER, TEXT? ARE ALL THE ENTRIES THE
SAME? VISUALIZING ALSO INCLUDES BEING ABLE TO SEE TIMELINES
FOR ENTRIES THAT ARE DATES.
MANIPULATING DATA INCLUDES GLOBAL SEARCHING AND
REPLACING, UPDATING ENTRIES SINGLY OR BY BATCH, ADDING NEW
DATA, REMOVING DATA, CHANGING THE DATA TYPES, AND MORE!

7. LET’S DO THE TOUR
• CREATE A PROJECT
• DIFFERENT VIEWS
• SEEING YOUR DATA
• MANIPULATING ROWS/COLUMNS
• CORRECTING ERRORS

8. HOW TO MAKE CHANGES TO DATA
• CHANGES TO COLUMNS
• SPLIT
• ADD
• REMOVE
• RENAME
• MOVE
• CHANGES CELLS (TO DATA ANYWHERE)
• EDIT CELLS USING CUSTOM OR DEFAULT TRANSFORMS, FILL
DOWN/BLANK, SPLIT/JOIN CELLS, CLUSTER/EDIT

9. AVAILABLE TRANSFORMATIONS
TRIM OR COLLAPSE WHITESPACES
UNESCAPE HTML ENTITIES
CHANGE THE CASE (TITLE, LOWER OR UPPER CASE)
CHANGE THE DATA TO NUMERIC, DATE OR TEXT

10. CUSTOM TRANSFORMATIONS
• JYTHON
• HTTP://WWW.JYTHON.ORG/
• HTTPS://GITHUB.COM/OPENREFINE/OPENREFINE/WIKI/JYTHON
• GREL (OPEN REFINE EXPRESSION LANGUAGE)
• HTTPS://GITHUB.COM/OPENREFINE/OPENREFINE/WIKI/GREL-FUNCTIONS
• REGULAR EXPRESSIONS
• HTTP://EN.WIKIPEDIA.ORG/WIKI/REGULAR_EXPRESSION
• HTTP://WWW.REGULAR-EXPRESSIONS.INFO/QUICKSTART.HTML

11. GREL
• SLICE
• EXAMPLE CHANGE “2010-05-31T01:10:0Z” TO “05/31/2010”
• VALUE.SLICE(5,7) + ‘/’ + VALUE.SLICE(8,10) + ‘/’ + VALUE.SLICE(0,4)
• YOU CAN ALSO USE:
• ADD A PREFIX
• “PREFIX” + VALUE
• SPLIT AND JOIN
• A:B:C:D:E -> B:C:D

12. REGULAR EXPRESSIONS
• TEXT PATTERN THAT ONE CAN USE WITH MANY MODERN
APPLICATIONS AND PROGRAMMING LANGUAGES
• REGULAR EXPRESSIONS COME IN FLAVORS
• .NET, JAVA, JAVASCRIPT, PERL, PYTHON, RUBY, …
• METACHARACTERS: 12 PUNCTUATION CHARACTERS THAT MAKE
REGULAR EXPRESSIONS WORK

13. REGULAR EXPRESSIONS
• CHARACTER CLASS ABBREVIATIONS

14. REGULAR EXPRESSIONS
• REMOVE THE “.” AT THE END OF A PHRASE
• VALUE.REPLACE(/[.]$/, “”)
• WHAT HAPPENS IF YOU JUST PUT /.$/ WITHOUT THE BRACKETS?
• REMOVE A STRING AT THE BEGINNING OF THE PHRASE WHERE THE
FIRST LETTER OF THE STRING IS UPPER OR LOWER CASE
• VALUE.REPLACE(/^W+S/, “”)
• TEST IT OUT
• HTTP://REGEXPAL.COM/

15. QUESTIONS?

16. RESOURCES
• USING OPEN REFINE … THE BOOK, QA76.9.D343 V47 2013
• OPEN REFINE DOCUMENTATION: HTTP://OPEN
REFINE.ORG/DOCUMENTATION.HTML
• OPEN REFINE COMMUNITY: HTTP://OPEN
REFINE.ORG/COMMUNITY.HTML
• CODE PROJECT ON REGULAR EXPRESSIONS:
HTTP://WWW.CODEPROJECT.COM/ARTICLES/9099/THE-MINUTE-
REGEX-TUTORIAL
• REGULAR EXPRESSIONS CHEAT SHEET:
HTTP://WWW.CHEATOGRAPHY.COM/DAVECHILD/CHEAT-
SHEETS/REGULAR-EXPRESSIONS/
• REGULAR EXPRESSIONS TESTER: HTTP://REGEXPAL.COM/ ,
HTTP://REGEX101.COM/